IMHO you over feeding (burning) your plants with nutrients.
I look at your diary:
Week 1 - nice looking perfect green seedlings, no feeding info
Week 2 - seedlings with issues, there is a feeding info.
You shouldn't blindly follow FOOP feeding recommendations, every plant is different and yours certainly do not need amount of nutrients your are feeding them. FOOP even cautions that over feeding can cause root burn.